The invention proceeds from a device and a method for metering a liquid into the exhaust tract of an internal combustion engine according to the preamble of the independent claims.
For the aftertreatment of exhaust gases from an internal combustion engine, DE 44 36 397 B4 discloses the delivery by a delivery element of a liquid, for example liquid urea solution or fuel, from a reservoir to an injection valve, which meters a required quantity of the liquid into the exhaust tract. Here the injection valve is arranged on the exhaust tract in such a way that its injection orifice is directed into the exhaust tract.
In operation very high temperatures can occur on the injection valve, particularly at its injection orifice, due to hot exhaust gases in the exhaust tract. This negative effect may be further exacerbated by the need to arrange the injection valve in proximity to hot components, such as the internal combustion engine, for example, or an exhaust gas turbocharger. There is the risk here of an unwanted thermal decomposition of the liquid in the injection valve or a formation of deposits in the injection orifice of the injection valve. The metering accuracy of the injection valve may thereby be impaired, which in extreme cases can lead to failure of the injection valve.
In order to avoid these very high temperatures in the injection valve, DE 10 2007 011 686 A1 discloses an injection valve with cooling in the area of the injection orifice. In addition, DE 10 2006 019 973 A1 discloses a metering system for providing reducing agents in the exhaust tract, in which a metering valve of the metering system can be cooled by a cooling circuit.